This invention relates to automotive heating systems in general, and specifically to means for speeding up the warm up process for a heating system.
Vehicle heating systems, at least those on internal combustion vehicles, generally divert a portion of the liquid coolant used to cool the engine to a heater core located in or near the interior, or cabin, of the vehicle. Air is blown over the heater core into the vehicle which, of course, can be no warmer than, and warm no sooner than, the liquid coolant in the heater core. The liquid coolant in the heater core, in turn, is substantially only as warm as, and becomes warm no sooner than, the coolant in the cooling jacket of the engine block from which it is diverted. Cabin heat is called for by the vehicle operator on a cold day, of course, but when the engine first starts up on a cold day, the engine block and coolant are naturally as cold as the ambient, and even a stationary vehicle will not achieve hot engine coolant right away. Since the vehicle is typically driven off soon after starting up, the warm up process is delayed even longer. While the radiator and cooling fan do not operate to cool the engine until it is hot, so called ram air enters the engine compartment through and under the grill, and blows forcefully over the engine block and its coolant jacket, especially at high speed. This tends to cool the engine block and delay the warm up process considerably.
Known devices and methods used to retard the ram air cooling process after cold start up generally include physically movable, additional vehicle structures, such as shields or louvers, which block the front air openings. These add expense and take up room under the hood. Larger vehicles, such as trucks and busses, actually place a separate screen temporarily over the outside of the grill. These are obviously inconvenient, and would not be considered suitable for a typical passenger vehicle.
The subject invention provides a means to speed cold start warm up which takes advantage of existing structure, and which operates essentially automatically and invisibly to the vehicle operator.
In the embodiment disclosed, the engine cooling (radiator) fan just behind the vehicle grill is driven by an electric motor, which is an increasingly common alternative to the older belt drive devices. During cold start up conditions, when cabin heat is requested, the fan direction is reversed. Now, rather than assisting air flow through the grill, in the same direction as the natural ram air flow, the fan actually retards or blocks the ram air flow. In effect, the equivalent of a physical blocking shield is temporarily provided, but without the need for a separate structure. When the engine coolant has become sufficiently hot, the fan is returned to normal operation.